I am in the process of designing a 2 car garage that I will start construction on shortly. It will be heated and insulated (I live in New Hampshire). Because I want to be able to wash my car in the winter, I am hoping to install some floor drains. They will only see gray water from vehicle washing.

My State Dept of Environmental Services has recommended against a dry well, due mostly to the fact that if anything bad gets in the dry well, no one sees it and it just quietly contaminates the ground.

The man suggested that I discharge the drains to the surface. How would this be done? Does anyone out there have any experience with such a set-up. How do you keep it from freezing up in the winter? How do you keep the animals out? I would greatly appreciate hearing from anyone with any experience in this area. Thank you very much.